Device for promtping use of vehicle seatbelts

ABSTRACT

A device for prompting the use of a vehicle seatbelt. The device includes a sensor and an alarm. The sensor is attached to the seatbelt so that it assumes a first angular position when the seatbelt is in an inoperative position and a second angular position when the seatbelt is in an operative position. The sensor includes a motion sensor responsive to motion of the vehicle when the sensor is in the first angular position. The sensor generates a signal indicative of motion of the vehicle occurring while the sensor is in the first position. The alarm is responsive to the signal and generate an alarm to prompt use of the seatbelt.

FIELD AND BACKGROUND OF THE INVENTION

The present invention relates to safety restraints and, in particular,to devices for prompting the occupants of a vehicle to use seatbelts.

It is known that the use of safety restraints in cars and other vehiclesgreatly reduces fatalities and serious injuries in the event of anaccident. Although seatbelts are now commonly fitted in all modern cars,drivers and passengers frequently forget to use them.

In order to remind people to use the seatbelts provided, some cars areprovided with seatbelt warning systems. These systems generally providea visual and/or audible warning signal typically from the moment the carignition is activated until the seatbelts are fastened. Such systemsemploy a sensor within the seatbelt locking mechanism, as well assensors within the seats of the car for sensing the presence of a driverand/or passenger. These sensors are all connected by means of wires tothe seatbelt warning system. The entire system is, in turn, connected tothe car ignition system.

Seatbelt warning systems of this type require specially designedseatbelt locking mechanisms, mounting of special sensors within theseats, and extensive wiring. As a result, they are expensive, difficultto service, and highly unsuitable for retrofitting to a car notoriginally fitted with such a system.

There is therefore a need for an inexpensive, easily fittable device forprompting the use of a vehicle seatbelt.

SUMMARY OF THE INVENTION

The present invention is of a device for prompting use of a vehicleseatbelt.

According to the teachings of the present invention there is provided, adevice for prompting the use of a vehicle seatbelt, the seatbelt beingdeployable from an inoperative position to an operative position, thedevice comprising: (a) a sensor unit attachable to the seatbelt so thatthe sensor unit assumes a first angular position when the seatbelt is inthe inoperative position and a second angular position when the seatbeltis in the operative position, the sensor unit including a motion sensorresponsive to motion of the vehicle when the sensor unit is in the firstangular position, the sensor unit generating a signal indicative ofmotion of the vehicle occurring while the sensor unit is in the firstposition; and (b) an alarm unit associated with the sensor unit, thealarm unit being responsive to the signal to generate an alarm to promptuse of the seatbelt.

According to a further feature of the present invention, there is alsoprovided a tilt sensor effective to prevent the motion sensor fromgenerating the electrical signal when the sensor unit is in the secondangular position.

According to a further feature of the present invention, the motionsensor is implemented as a tilt-dependent motion sensor.

According to a further feature of the present invention, there is alsoprovided a delay system, connected to the alarm unit, for preventingrepetition of the alarm for a predetermined time period after a previousgeneration of the alarm.

According to a further feature of the present invention, thepredetermined time period is in the range from about half-an-hour toabout an hour.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is herein described, by way of example only, withreference to the accompanying drawings, wherein:

FIG. 1 is a schematic perspective view of a first embodiment of a devicefor prompting use of a seatbelt, the device constructed and operativeaccording to the teachings of the present invention;

FIG. 2 is a schematic cross-sectional plan view of the device of FIG. 1;

FIG. 3 is a block diagram illustrating the principles of operation ofthe device of FIG. 1;

FIG. 4 is a logic circuit for use in the device of FIG. 1;

FIG. 5A is a schematic view of the device of FIG. 1 attached to aseatbelt which is in an inoperative position;

FIG. 5B is a schematic view of the device of FIG. 1 attached to aseatbelt which is in an operative position;

FIG. 6A is a schematic cross-sectional view of a tilt-dependent motionsensor for use in a second embodiment of a device for prompting use of aseatbelt, the device constructed and operative according to theteachings of the present invention, the tilt-dependent motion sensorbeing shown in a first angular position; and

FIG. 6B is a schematic cross-sectional view of the tilt-dependent motionsensor of FIG. 6A in a second angular position.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention is of a device for prompting use of a vehicleseatbelt.

The principles and operation of the device according to the presentinvention may be better understood with reference to the drawings andthe accompanying description.

Referring now to the drawings, FIGS. 1 and 2 show a first embodiment ofa device, generally designated 10, constructed and operative accordingto the teachings of the present invention, for prompting the use of avehicle seatbelt. Generally speaking, device 10 includes a sensor unitand an alarm unit. The sensor unit is attachable to the seatbelt so thatit assumes a first angular position when the seatbelt is in itsinoperative position, i.e., not connected, (FIG. 5A), and a secondangular position when the seatbelt is in its operative position, i.e.,when connected so as to restrain a passenger, (FIG. 5B). The sensor unitincludes a motion sensor which is responsive to motion of the vehiclewhen the sensor unit is in the first, inoperative, angular position togenerate an electrical signal. The alarm unit is responsive to theelectrical signal to generate an alarm reminding the user to engage theseatbelt.

FIG. 3 illustrates the principles of operation of device 10. Operationof device 10 starts when it is initially attached to a vehicle seatbeltwith a battery or other suitable electrical power supply in place. Thisinitial stage of operation is represented by block 42. Device 10 thenbegins to detect motion (block 44) of the vehicle indicative of currentor imminent use. Motion, in this context, refers to both translationalmovement and to vibrations such as are produced when a vehicle engine isstarted. If no motion is detected, device 10 returns to start 42. Ifmotion is detected, device 10 then checks the angular position of theseatbelt, indicative of whether the seatbelt is in use orconnected/engaged (block 46). If the seatbelt is in use, device 10returns to start 42. If the seatbelt is not in use, an alarm isactivated (block 48) to prompt the user to connect the seatbelt. Afteractivation of an alarm 48, device 10 becomes inactive for a delay period(block 50), typically of from about 1/2-1 hour, thereby preventingunwanted repetition of the alarm, before returning to start 42. Itshould be noted that the logical order of these steps is not uniquelydefined. For example, the order of blocks 44 and 46 may be reversedwithout changing the overall operation of device 10.

Referring now to the structural features of device 10 more specifically,FIG. 1 shows the exterior of device 10. Device 10 has a housing 12 whichcontains the functional components of device 10. Housing 12 may be madeof any suitable materials including, but not limited to, moldedplastics, thin metal or other light materials. Device 10 also featuresan attachment mechanism 14 for attaching device 10 to a seatbelt.Attachment mechanism 14, as depicted in FIG. 1, is a clip, but variousother mechanisms for attaching device 10 may be used. Examples includeelastic straps, compact clamping mechanisms of all kinds, bolts, andvarious types of adhesive. Preferably, attachment mechanism 14 isattached to the seatbelt removably, semi-permanently or permanentlywithout damaging the integrity of the seatbelt. It is a particularfeature of attachment mechanism 14 that it prevents rotation of device10 relative to the seatbelt, so that the angular position of device 10is directly correlated to that of the seatbelt. Preferably, attachmentmechanism 14 is also designed to produce a defined orientation of device10 relative to the seatbelt. For example, a portion of attachmentmechanism 14 may be shaped to abut an edge of the seatbelt so as toalign device 10 at a specific angle relative to the seatbelt. Thisinsures correct positioning of the tilt sensor of device 10, as will bedescribed below.

A number of perforations 16 may be provided in housing 12 for increasingthe transmission of an audible alarm through housing 12. If a visualalarm signal is to be provided either in addition to, or as analternative for, an audible alarm, at least one electric bulb with atransparent protective cover (not shown) is built into housing 12.Housing 12 is preferably also provided with an easily removable batterycompartment lid (not shown) to enable easy replacement of an internalbattery.

FIG. 2 shows the internal components of device 10. A sensor unit 18includes a motion sensor 20 and a tilt sensor 22, both connected to aprocessor 24. Processor 24 is connected through a delay system 26 to analarm unit 28 with a speaker 30. A battery 32 supplies electrical powerto each component through a system of wires or rails represented bydashed lines 34.

Motion sensor 20 may be any type of motion or vibration sensor. Thesensitivity of motion sensor 20 is such that, when device 10 is fittedin a vehicle, normal vibration caused by wind or passing cars while thevehicle is stationary will not be detected, whereas movement of thevehicle itself will be detected. Preferably, the sensitivity is tunedsuch that the opening of the vehicle doors will not be detected, but theclosing of the doors, or the starting of the vehicle ignition will bedetected.

Tilt sensor 22 may be any type of tilt sensor or inclination meter. In apreferred embodiment, tilt sensor 22 provides a simple yes/no indicationof whether a line defined as the axis of tilt sensor 22 is within agiven range relative to the vertical. Typically, this range is betweenabout ±150 and ±200. Preferably, tilt sensor 22 is symmetrical oninversion, meaning that it will indicate "close to vertical" if the axisis within either the range ±15° or the range 165°-195° to an upwardvertical. This enables device 10 to be installed in either senserelative to the direction of the seatbelt. Alternatively, a moresophisticated attitude meter may be used. In this case, processor 24 isprogrammed appropriately to analyze the output from the sensor todetermine whether the attitude of device 10 lies within the range ofinterest.

Tilt sensor 22 is mounted within device 10 such that, when device 10 ismounted on a seatbelt in its inoperative position, the axis of tiltsensor 22 is approximately vertical. Typically, in the case ofconventional inertia-reel seatbelts in which the inoperative position isapproximately vertical, the axis of tilt sensor 22 is alignedapproximately parallel to the length of the seatbelt. In certainembodiments, tilt sensor 22 is mounted on a rotatable base so that itcan be aligned for use on non-standard seatbelt types. Alternatively,tilt sensor 22 is self-calibrating, setting its axis to be the verticalof its current position. The self-calibration may be actuated eithermanually on installation of device 10 or automatically in the event ofthe orientation remaining constant for a period of a number of hours.

Processor 24 processes the outputs of motion sensor 20 and tilt sensor22 to generate an electrical signal indicative of failure to use aseatbelt. In its simplest form, processor 24 is a simple combination oflogic gates, or even a single logic gate, producing a signal when motionsensor 20 detects motion, indicating that the vehicle is in use, andtilt indicator 22 indicates that the seatbelt is in an inoperativeposition. Alternatively, a similar function may be performed by a simplecombination of electronic components. Where more sophisticated sensorsare used, processor 24 is designed to analyze the output from thesensors to extract the required information. Processor 24 mayadditionally analyze the output of motion sensor 20 to distinguishbetween different types of motion. Processor 24 may also controlself-calibration of tilt sensor 22, as described above.

Delay system 26 serves to prevent repetition of an alarm for apredetermined time interval after a previous alarm. This feature servesto prevent annoying recurrence of an ineffective alarm signal, forexample, from a seatbelt belonging to a seat which is not in use.Preferably, the predetermined time period is in the range of from abouthalf-an-hour to about an hour, thereby covering the duration of mostjourneys. When no alarm has been produced within this time period, delaysystem 26 is inactive, allowing any signal produced by processor 24 topass directly to alarm unit 28. Once a signal has reached alarm unit 28,delay system 26 effectively blocks transmission of further alarm signalsuntil the predetermined time period has elapsed.

Alarm unit 28 is responsive to the electrical signal from processor 24to generate an alarm to prompt use of the seatbelt. Typically, the alarmis an audible alarm produced through speaker 30, or some other audiosignal generator, such as a transducer or bell. Preferably, alarm unit28 generates a short series of spaced pulses or spaced multiple pulses.Alarm unit 28 may additionally, or alternatively, be connected to alight bulb (not shown) for producing a visual alarm signal.

It should be appreciated that the specific interconnection of thecomponents as shown in FIG. 2, as well as the subdivision of processor24, delay system 26 and alarm unit 28, are somewhat arbitrary. Forexample, delay system 26 could be implemented as a feedback loopreceiving an input from alarm unit 28 and providing a third input to aslightly modified processor 24, without changing the functionality ofthe components. Similarly, processor 24, delay system 26 and alarm unit28 may be combined into a single microprocessor chip.

Referring now to FIG. 4, there is shown a possible logic circuit,generally designated 52, for use in device 10. Logic circuit 52 may beused in a case that motion sensor 20 produces a binary output 54 wherein"1" represents motion and "0" represents lack of motion, and that tiltsensor 22 produces a binary output 56 wherein "1" represents anear-vertical angular position corresponding to an inoperative positionof a seatbelt and "0" corresponds to an operative position of aseatbelt.

Logic circuit 52 exemplifies an alternative implementation of delaysystem 26 as delay logic 58. In this case, delay logic 58 receives aninput 60 from alarm unit 28 indicative of alarm unit 28 having beenactivated. Delay logic 58 produces a binary output 62 which takes thevalue 0 for the predetermined time period after activation of alarm 28,and 1 at other times. Outputs 54, 56 and 62 are combined in a tripleAND-gate 64 which supplies a binary input 66 to alarm unit 28. In theevent that outputs 54, 56 and 62 all take the value 1, indicating thepresence of motion, an inoperative position of the seatbelt and therequired delay period since the last alarm, input 66 will take the value1, thereby activating alarm unit 28.

The use of device 10 will now be described with reference to FIGS. 5Aand 5B. FIG. 5A shows device 10 attached to a seatbelt 70 in aninoperative position. As described above, device 10 is attached toseatbelt 70 such that, when seatbelt 70 is in an inoperative position,tilt sensor 22 of sensor unit 18 is in a first angular position relativeto the vertical, V.

For purposes of illustration, line 72 represents an axis x definedrelative to tilt sensor 22 such that, when tilt sensor 22 is attached toseatbelt 70 in an inoperative position, axis x is approximately parallelto vertical V. This alignment may be achieved either by alignment ofdevice 10 with seatbelt 70 when it is first attached, or byself-calibration of tilt sensor 22 after attachment, as mentioned above.As long as seatbelt 70 is not in use, axis x remains within a definedrange of angles, typically from between about ±15° and about ±200, fromvertical V. Within this range, tilt sensor 22 allows motion sensor 20 togenerate an electrical signal to activate an alarm in response tocertain amounts and/or types of motion, as described above.

FIG. 5B shows device 10 attached to a seatbelt 70 in an operativeposition. In this position, sensor unit 18 is in a second angularposition such that axis x is rotated significantly out of alignment withvertical V. Tilt sensor 22 is then effective in preventing motion sensor20 from actuating an alarm, as described above.

It should be noted that, since tilt sensor 22 is typically sensitive toinclinations of more than about ±15° and about ±20°, most of belt 70will tilt sufficiently between its operative and inoperative positionsto allow correct functioning of device 10. Thus, device 10 may beattached to almost any part of seatbelt 70 which is exposed in theinoperative position. Alternatively, device 10 may be attached to aseatbelt buckle, or any other part of a seatbelt assembly whoseorientation varies sufficiently between the seatbelt's operative andinoperative positions.

With reference now to FIGS. 6A and 6B, a second embodiment of a device,constructed and operative according to the teachings of the presentinvention, for prompting use of a vehicle seatbelt will be described.This second embodiment is similar in structure and identical in functionto the first embodiment described above, differing only in that motionsensor 20 and tilt sensor 22 are now replaced by a single tilt-dependentmotion sensor.

FIG. 6A shows a tilt-dependent motion sensor, generally designated 80,constructed and operative according to the teachings of the presentinvention, for use in the second embodiment of a device for promptinguse of a vehicle seatbelt. Sensor 80 has a bulb-like hollow body 82 withtwo recesses 84. Each recess 84 is provided with at least two electriccontacts 86. A conductive ball 88 is free to move within body 82. Forpurposes of illustration, a line 90 represents an axis x definedrelative to sensor 80 such that it is parallel to a line through bothrecesses 84. A vertical V is also shown.

Body 82 is shaped so that, when sensor 80 is in a first angular positionas shown in FIG. 6A, i.e., that axis x is within a given range of anglesfrom vertical V, conductive ball 88 rolls into one of recesses 84.Conductive ball 88 thus lies in contact with electric contacts 86thereby completing an electric circuit (not shown). In this position,movement or vibration of sensor 80 causes momentary loss of contactbetween conductive ball 88 and electric contacts 86, thereby breakingand recompleting the electric circuit. In this embodiment, processor 24includes a combination of electronic components or logic circuitryresponsive to repeated opening and closing of a circuit to generate anelectric signal to activate alarm unit 28.

FIG. 6B shows sensor 80 in a second angular position in which axis x isoutside the given range of angles from vertical V. Body 82 is shaped sothat, when sensor 80 is in this second angular position, conductive ball88 rolls away from recesses 84, thereby avoiding contact with electriccontacts 86. Thus, vibration and movement of sensor 80 while in thisposition will not result in completion of the electric circuit, and willnot cause processor 24 to activate alarm unit 28.

It will now be apparent that motion sensor 20 and tilt sensor 22 of thefirst embodiment of the present invention may be replaced by sensor 80,requiring only minor adaptation of processor 24, and without changingthe functionality of the device. Hence, in all other respects, thestructure and operation of the second embodiment of the presentinvention may be understood by analogy from the above drawings anddescription of the first embodiment.

It will be understood that the present invention has been described, byway of example, in a limited number of embodiments. Many othervariations may be made without departing from the scope and the spiritof the present invention.

What is claimed is:
 1. A device for prompting use of a vehicle seatbelt,the seatbelt being deployable between from an inoperative position to anoperative position, the device comprising:(a) a sensor unit attachableto the seatbelt so that said sensor unit assumes a first angularposition when the seatbelt is in the inoperative position and a secondangular position when the seatbelt is in the operative position, saidsensor including a motion sensor responsive to motion of the vehicle atleast when said sensor unit is in said first angular position, saidsensor unit generating a signal indicative of motion of the vehicleoccurring while said sensor unit is in said first angular position; and(b) an alarm unit associated with said sensor unit, said alarm unitbeing responsive to said signal to generate an alarm to prompt use ofthe seatbelt.
 2. The device of claim 1, further comprising a tilt sensoreffective to prevent said motion sensor from generating said electricalsignal when said sensor unit is in said second angular position.
 3. Thedevice of claim 1, wherein said motion sensor is implemented as atilt-dependent motion sensor.
 4. The device of claim 1, furthercomprising a delay system, connected to said alarm unit, for preventingrepetition of said alarm for a predetermined time period after aprevious generation of said alarm.
 5. The device of claim 4, whereinsaid predetermined time period is in the range from about half-an-hourto about an hour.